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Abstract：
Successful seedling establishment depends on the optimum depth of seed placement especially in drought-prone conditions, providing an opportunity to exploit subsoil water and increase winter survival in winter wheat. Coleoptile length is a key determinant for the appropriate depth at which seed can be sown. Thus, understanding the genetic basis of coleoptile length is necessary and important for wheat breeding. We conducted a genome-wide association study (GWAS) using a diverse panel of 298 winter wheat genotypes to dissect the genetic architecture of coleoptile length. We identified nine genomic regions associated with the coleoptile length on seven different chromosomes. Of the nine genomic regions, five have been previously reported in various studies, including one mapped to previously known Rht-B1 region. Three novel quantitative trait loci (QTLs), QCL.sdsu-2AS, QCL.sdsu-4BL, and QCL.sdsu-5BL were identified in our study. QCL.sdsu-5BL has a large substitution effect which is comparable to Rht-B1\'s effect and could be used to compensate for the negative effect of Rht-B1 on coleoptile length. In total, the nine QTLs explained 59% of the total phenotypic variation. Cultivars \'Agate\' and \'MT06103\' have the longest coleoptile length and interestingly, have favorable alleles at nine and eight coleoptile loci, respectively. These lines could be a valuable germplasm for longer coleoptile breeding. Gene annotations in the candidate regions revealed several putative proteins of specific interest including cytochrome P450-like, expansins, and phytochrome A. The QTLs for coleoptile length linked to single-nucleotide polymorphism (SNP) markers reported in this study could be employed in marker-assisted breeding for longer coleoptile in wheat. Thus, our study provides valuable insights into the genetic and molecular regulation of the coleoptile length in winter wheat.
摘要：
成功的幼苗建立取决于种子放置的最佳深度，尤其是在干旱易发的条件下，提供了一个利用地下土壤水和增加冬小麦冬季存活率的机会。胚芽鞘长度是种子可以播种的适当深度的关键决定因素。因此，了解胚芽鞘长度的遗传基础对小麦育种是必要和重要的。我们使用298种冬小麦基因型的不同小组进行了全基因组关联研究（GWAS），以剖析胚芽鞘长度的遗传结构。我们在七个不同的染色体上鉴定了与胚芽鞘长度相关的九个基因组区域。在九个基因组区域中，以前在各种研究中已经报道了五种，包括映射到先前已知的Rht-B1区域的一个。三个新的数量性状基因座（QTLs），QCL。sdsu-2AS,QCL。sdsu-4BL,和QCL。在我们的研究中鉴定了sdsu-5BL。QCL。sdsu-5BL具有较大的替代效应，与Rht-B1的效应相当，可用于补偿Rht-B1对胚芽鞘长度的负面影响。总的来说,9个QTL解释了总表型变异的59%。品种\'玛瑙\'和\'MT06103\'有最长的胚芽鞘长度和有趣的，在9个和8个胚芽鞘位点有有利的等位基因，分别。这些品系可能是较长的胚芽鞘育种的宝贵种质。候选区域中的基因注释揭示了几种特定感兴趣的推定蛋白质，包括细胞色素P450样，expansins,和植物色素A。本研究报道的与单核苷酸多态性（SNP）标记相关的胚芽鞘长度QTL可用于标记辅助育种，以促进小麦中更长的胚芽鞘。因此，我们的研究为冬小麦胚芽鞘长度的遗传和分子调控提供了有价值的见解。
